1. Field of the Invention
The present invention relates generally to aerosol generators and, more particularly, to vapor driven aerosol generators. The aerosol generators of the invention are able to generate aerosols without requiring the use of compressed gas propellants. The present invention also relates to methods for generating an aerosol. The present invention has particular applicability to the generation of aerosols containing medicated material.
2. Description of the Related Art
Aerosols are gaseous suspensions of fine solid or liquid particles and are useful in a wide variety of applications. For example, medicated liquids and powders may be administered in aerosol form. Such medicated aerosols include, for example, materials which are useful in the treatment of respiratory ailments, in which case the aerosols may be inhaled into a patient""s lungs. Aerosols may also be used in non-medicinal applications including, for example, dispensing air fresheners, applying perfumes and delivering paints and/or lubricants.
In aerosol inhalation applications, it is typically desirable to provide an aerosol having an average mass median particle diameter of less than 2 microns to facilitate deep lung penetration. Most known aerosol generators are incapable of generating aerosols having an average mass median particle diameter less than from 2 to 4 microns. Also, in certain applications, it is generally desirable to deliver medicated material at high flow rates, for example, above 1 mg per second. Most known aerosols suited for delivering medicated material are incapable of delivering material at such high flow rates while maintaining a suitable average mass median particle diameter. In addition, most known aerosol generators deliver an imprecise amount of aerosol compared with the amount of aerosol that is intended to be delivered.
The related art discloses aerosol generators which employ various techniques for delivering an aerosol. A particularly useful technique involves volatilizing a fluid and ejecting the volatilized fluid into the atmosphere. The volatilized fluid subsequently condenses, thereby forming an aerosol. See, for example, commonly assigned U.S. Pat. No. 5,743,251, the entire contents of which document are hereby incorporated by reference. Such aerosol generators may eliminate or conspicuously reduce some or all of the aforementioned problems associated with the known aerosol generators. However, since these aerosol generators employ heat-generating systems, heat resistive material and, in some cases, various control devices, pumps and valves, the manufacture and assembly of such aerosol generators can be complicated and expensive.
In light of the foregoing, there exists a need in the art for the provision of an aerosol generator which overcomes or conspicuously ameliorates the above described shortcomings in the related art. Accordingly, it is an object of the present invention to provide a vapor driven aerosol generator which produces an aerosol from a fluid by volatilizing the fluid and directing the volatilized fluid therefrom.
Other objects and aspects of the present invention will become apparent to one of ordinary skill in the art upon review of the specification, drawings and claims appended hereto.
The invention provides an aerosol generator which includes a fluid passage located between opposed layers of a laminate. The layers can comprise copper sheets and the fluid passage can comprise a space formed by locating a mandrel between the copper sheets, bonding the layers together and removing the mandrel. A heater can be arranged to heat fluid in the passage into a gaseous state such that the vaporized fluid ejected from the fluid passage condenses in ambient air and forms an aerosol.
The laminate can include ceramic layers sandwiching the copper layers and the ceramic layers can be bonded to the copper layers at the time the copper layers are bonded together. The heater can comprise a layer of resistance heating material located on one or more of the ceramic layers so as to conduct heat into the fluid passage.